Re: Unable to configure bridge networking on Ubuntu 21.04 host (Netplan) / MacOS guest

[Adam Kessel]

On 9/17/2021 8:00 PM, Adam Kessel wrote:

> I'm
>       running Ubuntu 21.04 host (Netplan networking) and MacOS guest
>       (from macOS-Simple-KVM). Attempting to get bridge networking to
>       work either from qemu CLI or via virt-manager. While NAT works
>       fine, I have not had any luck with bridge networking -- the guest
>       cannot connect to the Internet and is unable to get an IP address
>       via DHCP.
>       
>       
>       I've followed the various tutorials exactly, e.g.
> https://fabianlee.org/2019/04/01/kvm-creating-a-bridged-network-with-netplan-on-ubuntu-bionic/
>       ,
> https://cplatform99.blogspot.com/2019/03/how-to-configure-linux-kvm-bridge-on.html
>       ,
> https://levelup.gitconnected.com/how-to-setup-bridge-networking-with-kvm-on-ubuntu-20-04-9c560b3e3991
>       ,
> https://www.answertopia.com/ubuntu/creating-an-ubuntu-kvm-networked-bridge-interface/
>       
>       I've tried setting both the Ethernet interface and the bridge
>       interface to DHCP and with statically configured IP addresses.
>       I've also tried a LAN-valid static IP address on the guest as well
>       as DHCP. No combination of these settings gets me through to the
>       network from the guest. I've tried going through the virt-manager
>       GUI and also manually crafting qemu command-line switches. I've
>       tried tun/tap as well as just connecting directly to br0. I've
>       tried disabling my firewall. I do have IP Forwarding configured on
>       the host.
>       
>       
>       My host has a very simple setup -- just one network card, IP
>       address set by DHCP.
>       
>       
>       Can anyone point me to a dead-simple, failproof/foolproof method
>       for enabling bridge networking with this setup? Is there something
>       that changed with Ubuntu 21.04 (either with networking or the
>       latest qemu) such that these older tutorials aren't working? Any
>       suggestions for how to troubleshoot?
>       
>       
>     
    Figured it out! For the record, the missing piece was:

create /etc/sysctl.d/99-netfilter-bridge.conf

net.bridge.bridge-nf-call-ip6tables = 0

net.bridge.bridge-nf-call-iptables = 0

net.bridge.bridge-nf-call-arptables = 0

run

sysctl -p /etc/sysctl.d/99-netfilter-bridge.conf

and make sure br_netfilter module is loaded at boot

Now the bridge connects successful to the guest OS regardless of which technique I use.

Adam